This invention relates to a magnetic head employed for e.g., a video tape recorder. More particularly, it relates to such magnetic head having improved abrasion resistance.
In FIG. 1, there is shown a magnetic head made up of a pair of magnetic core halves 33m, 33n bonded to each other with a magnetic gap g3 defined between abutting surfaces of the magnetic core halves 33m, 33n. The magnetic core halves 33m, 33n are formed by bonding single-crystal ferrite pieces 31m, 31n and polycrystal ferrite pieces 32m, 32n to each other to form a junction ferrite. The magnetic head thus formed has its upper most portion, that is a surface configured for having sliding contact with a magnetic recording medium, constituted by the single-crystal ferrite pieces 31m, 31n, while having its lower most portion, that is its bottom surface, constituted by the polycrystal ferrite pieces 32m, 32n.
With the above-described magnetic head, the magnetic gap g3 formed at the junction portion of the magnetic core halves 33m, 33n and the top of the surfaces of the single-crystal ferrite pieces 31m, 31n on which slides the magnetic recording medium, referred to hereinafter as an R-TOP, are designed to be coincident with each other, so that the magnetic recording medium will be contacted with the magnetic head at the site of the magnetic gap g3.
This type of the magnetic head is effective to reduce the sliding noise since the single-crystal ferrite pieces 31m, 31n are of a small volume and the polycrystal ferrite pieces 32m, 32n take up a major portion of the volume of the magnetic head.
In addition, with such magnetic head, superior electro-magnetic conversion characteristics may be realized by selecting the orientation of the atomic plane of the single-crystal ferrite pieces 31m, 31n so that a surface 31a of the magnetic head on which slides the magnetic recording medium is the (211) plane, the gap surface defined by the abutting surfaces of the magnetic core halves is the (111) plane and the lateral surface 31c corresponding to the lateral surface of the magnetic head is the (110) plane, and by setting the direction A3 of the &lt;100&gt;crystal axis of the single-crystal ferrite piece 31m so as to be symmetrical with respect to the direction A4 of the &lt;100&gt;crystal axis of the opposite-side single-crystal ferrite piece 31n on both sides of the magnetic gap g3.
However, if the direction A3 of the &lt;100&gt;crystal axis of the single-crystal ferrite piece 31m is set so as to be symmetrical with respect to the direction A4 of the &lt;100&gt;crystal axis of the single-crystal ferrite piece 31n on both sides of the magnetic gap g3, as shown in Figs.2 and 3, partial advancing abrasion of the magnetic core half 33m differs from that of the opposite side magnetic core half since the angle of the crystal axis of the single-crystal ferrite core 31m with respect to the sliding direction B of the magnetic recording medium differs from that of the opposite side single-crystal ferrite core 31n, as a result of which partial advancing abrasion, that is an abrasion advancing non-uniformly for the magnetic core halves 33m, 33n, is produced.
If such partial advancing abrasion is produced, a so-called R-TOP offset T is incurred between the position R of the R-TOP and the position G of the magnetic gap g3, as shown in FIGS. 2 and 3, so that the position G of the magnetic gap g3 becomes non-coincident with the position R of the R-TOP thus deteriorating abutting contact between the magnetic recording medium and the magnetic head. That is, the contact position between the magnetic recording medium and the magnetic head is an offset position R due to the partial advancing wear, so that the magnetic recording medium cannot be contacted with the magnetic head at the site of the magnetic gap g3.